1. Field of the invention
The invention is related to an electric balance with a measured value receiver for generating a weight-dependent signal, having a digital signal processing unit with means for detecting disturbances which affect the measured value receiver (sensor) and with means for correcting the error of the measured value receiver which result from these interfering disturbances.
2. Description of the Prior Art
Balances of this type are known, for example, from DE-OS No. 32 13 016, which describes in particular the correction of temperature errors. DE-OS No. 31 06 534 teaches the use of moisture and pressure sensors to correct corresponding dependencies on moisture of pressure of the measured value receiver.
A disadvantage of these known balances is the fact that only the instantaneous value of a particular disturbance variable can be detected and calculated. The behavior in time of the particular sensor must therefore be adapted to the behavior in time of the measured valued receiver. In the case of temperature sensor, for example, this must occur by means of a properly selected attachment point, properly selected heat capacity and properly selected heat resistance to the attachment point. However, this adaptation of the behavior in time is bothersome and also possible only to a limited extent. This is especially, the case, since the behavior in the time of the measured value receiver, which is constructed with many different individual parts, can not be represented by a simple mathematical relation. Moreover, this adaptation can be optimally performed for only one variable to be corrected, such as, for example, the sensitivity, since in general each variable to be corrected has a different behavior in time. However, when errors are corrected in the unit, all errors, if possible, should be corrected, thus, in addition to sensitivity errors also zero point errors and linearity errors.